Heart sounds-based pacing optimization

Abstract

An implantable medical device receives both heart sound and electrogram signals. A processor within the implantable medical device extracts physiologically relevant information from both the heart sound signal and the electrogram signal. Based on the extracted physiologically relevant information a set of pacing parameters is evaluated. In certain examples, the values of the pacing parameters may be changed by the implantable medical device in response to the physiologically relevant information extracted from the heart sound signal and the electrogram signal.

The invention claimed is: 
     
       1. A method comprising:
 obtaining heart sounds from an implanted heart sound sensor; 
 obtaining an electrogram (EGM) from electrodes of an implantable device; 
 generating one or more acoustic cardiographic metrics based on at least one of the heart sounds and the electrogram for a set of cardiac pacing parameters, the set of cardiac pacing parameters including a plurality of pacing parameters; 
 wherein the acoustic cardiographic metrics include one or more of:
 an indication of atrioventricular (AV) dyssynchrony based on at least an interval from heart sound S 2  to heart sound S 1 ; 
 an indication of interventricular (VV) dyssynchrony based on a splitting of at least one of heart sound S 1  and heart sound S 2 ; 
 an indication of left intraventricular dyssynchrony based on at least one of electromechanical activation delay (EMAT), 
 EMAT plus S 1  duration, 
 heart sound M 1  duration, and 
 heart sound A 2  duration, 
 
 a surrogate for a myocardial performance index (MPI) based at least on a duration heart sound S 1  and a duration of heart sound S 2 ; 
 an indication of left ventricle (LV) fill time based on the interval between heart sound S 2  and heart sound S 1 ; and 
 an indication of LV contractility based on at least one of:
 a ratio of EMAT plus heart sound S 1  duration divided by the interval between heart sound S 1  and heart sound S 2 ; 
 the ratio of EMAT plus S 1  duration divided by an R to R interval of the EGM, or 
 an indication of hypertension based on at least one of:
 heart sound S 1  splitting and heart sound S 2  splitting, 
 relative changes of intensity of M 1  and heart sound T 1  over a predetermined period of time, 
 relative change in a A 2  to heart sound P 2  amplitude ratio over a predetermined period of time, 
 
 variability in Q wave to heart sound A 2  interval (Q-A 2 ) over time, or heart sound S 4 ; and 
 
 wherein the acoustic cardiographic metric comprising the indication of VV dyssynchrony is based on the splitting of heart sound S 1  and heart sound S 2 , the method further comprising adjusting one or more cardiac pacing parameters to obtain an S 1  split between M 1  and T 1  that is between approximately 20 and 40 ms and an S 2  split between A 2  and P 2  that is approximately 20 ms. 
 
     
     
       2. A method comprising:
 obtaining heart sounds from an implanted heart sound sensor; 
 obtaining an electrogram (EGM) from electrodes of an implantable device; 
 generating one or more acoustic cardiographic metrics based on at least one of the heart sounds and the electrogram for a set of cardiac pacing parameters, the set of cardiac pacing parameters including a plurality of pacing parameters; 
 wherein the acoustic cardiographic metrics include one or more of:
 an indication of atrioventricular (AV) dyssynchrony based on at least an interval from heart sound S 2  to heart sound S 1 ; 
 an indication of interventricular (VV) dyssynchrony based on a splitting of at least one of heart sound S 1  and heart sound S 2 ; 
 
 an indication of left intraventricular dyssynchrony based on at least one of
 electromechanical activation delay (EMAT), 
 EMAT plus S 1  duration, 
 heart sound M 1  duration, and 
 heart sound A 2  duration, 
 
 a surrogate for a myocardial performance index (MPI) based at least on a duration heart sound S 1  and a duration of heart sound S 2 ; 
 an indication of left ventricle (LV) fill time based on the interval between heart sound S 2  and heart sound S 1 ; and 
 an indication of LV contractility based on at least one of:
 a ratio of EMAT plus heart sound S 1  duration divided by the interval between heart sound S 1  and heart sound S 2 ; 
 the ratio of EMAT plus S 1  duration divided by an R to R interval of the EGM, or 
 an indication of hypertension based on at least one of:
 heart sound S 1  splitting and heart sound S 2  splitting, 
 relative changes of intensity of M 1  and heart sound T 1  over a predetermined period of time, 
 relative change in a A 2  to heart sound P 2  amplitude ratio over a predetermined period of time, 
 
 variability in Q wave to heart sound A 2  interval (Q-A 2 ) over time, or heart sound S 4 ; and 
 
 further comprising adjusting one or more cardiac pacing parameters based on the indication of LV filling time to obtain an interval between S 2  and S 1  that is greater than 40% of an R to R interval of the EGM. 
 
     
     
       3. The method of  claim 2 , further comprising evaluating at least one of the cardiac pacing parameters based on at least one acoustic cardiographic metric, the evaluation comprising varying the at least one cardiac pacing parameter over a predetermined range at a predetermined interval and storing a corresponding acoustic cardiographic metric value for each variation of the at least one cardiac pacing parameter, and comparing the stored acoustic cardiographic metric values. 
     
     
       4. The method of  claim 2 , further comprising providing pacing according to the set of cardiac pacing parameters. 
     
     
       5. The method of  claim 4 , wherein the pacing includes cardiac resynchronization therapy. 
     
     
       6. The method of  claim 2 , further comprising evaluating at least one of the indications of hypertension, and based on the evaluation of the at least one indication of hypertension, generating a diagnosis of hypertension. 
     
     
       7. The method of  claim 6 , further comprising providing the diagnosis of hypertension to a remote device. 
     
     
       8. The method of  claim 6 , furthering comprising modifying the set of cardiac pacing parameters in response to the diagnosis of hypertension. 
     
     
       9. The method of  claim 1 , further comprising evaluating effectiveness of the cardiac pacing parameters based on at least one of the acoustic cardiographic metrics. 
     
     
       10. The method of  claim 9 , further comprising:
 generating a first acoustic cardiographic metric value for one of the acoustic cardiographic metrics corresponding to a first parameter value of one of the cardiac pacing parameters; 
 generating a second acoustic cardiographic metric value for the one of the acoustic cardiographic metrics corresponding to a second parameter value of the one of the cardiac pacing parameters; 
 comparing the first acoustic cardiographic metric value and the second acoustic cardiographic metric value; and 
 determining, based on the comparison, which of the first parameter value and the second parameter is more effective. 
 
     
     
       11. The method of  claim 1  further comprising determining, based on the acoustic cardiographic metrics, a fusion band. 
     
     
       12. The method of  claim 11 , wherein an AV delay pacing parameter is set within the fusion band. 
     
     
       13. The method of  claim 1 , further including choosing an atrioventricular delay pacing parameter based on a change in heart sound S 2  timing. 
     
     
       14. The method of  claim 2 , further comprising adjusting one or more of the cardiac pacing parameters based on at least one acoustic cardiographic metric. 
     
     
       15. A device comprising:
 a heart sound sensor configured to obtain a heart sound signal; 
 an electrogram (EGM) sensor configured to obtain an electrogram; and 
 a processor configured to generate one or more acoustic cardiographic metrics based on at least one of the heart sound signal received from the heart sound sensor and the EGM received from the EGM sensor for a set of cardiac pacing parameters, wherein the acoustic cardiographic metrics include one or more of: 
 an indication of atrioventricular (AV) dyssynchrony based on at least an interval from heart sound S 2  to heart sound S 1 ; 
 an indication of interventricular (VV) dyssynchrony based on a splitting of at least one of heart sound S 1  and heart sound S 2 ; 
 an indication of left intraventricular dyssynchrony based on at least one of
 electromechanical activation delay (EMAT), 
 EMAT plus S 1  duration, 
 heart sound M 1  duration, and 
 heart sound A 2  duration, 
 
 a surrogate for a myocardial performance index (MPI) based at least on a duration heart sound S 1  and a duration of heart sound S 2 ; 
 an indication of left ventricle (LV) filling time based on the interval between heart sound S 2  and heart sound S 1 ; and 
 an indication of LV contractility based on at least one of:
 the ratio of EMAT plus heart sound S 1  duration divided by the interval between heart sound S 1  and heart sound S 2 ; 
 the ratio of EMAT plus S 1  duration divided by an R to R interval of the EGM: 
 an indication of hypertension based on at least one of:
 heart sound S 1  splitting and heart sound S 2  splitting, 
 relative changes of intensity of M 1  and heart sound T 1  over a predetermined period of time, 
 relative change in a A 2  to heart sound P 2  amplitude ratio over a predetermined period of time, 
 
 variability in Q wave to heart sound A 2  interval (Q-A 2 ) over time, or heart sound S 4 ; and 
 
 wherein the acoustic cardiographic metric comprises the indication of VV dyssynchrony, and is based on the splitting of heart sound S 1  and heart sound S 2 , and the processor is further configured to one or more cardiac pacing parameters to obtain an S 1  split between M 1  and T 1  that is between approximately 20 and 40 ms and an S 2  split between A 2  and P 2  that is approximately 20 ms. 
 
     
     
       16. The device of  claim 15 , wherein the processor is further configured to evaluate the effectiveness of the cardiac pacing parameters based on at least one of the acoustic cardiographic metrics. 
     
     
       17. The device of  claim 16 , wherein the processor is further configured to:
 generate a first acoustic cardiographic metric value for one of the acoustic cardiographic metrics corresponding to a first parameter value of one of the cardiac pacing parameters; 
 generate a second acoustic cardiographic metric value for the one of the acoustic cardiographic metrics corresponding to a second parameter value of the of the one of the cardiac pacing parameters; 
 compare the first acoustic cardiographic metric value and the second acoustic cardiographic metric value; and 
 determine, based on the comparison, which of the first parameter value and the second parameter is more effective. 
 
     
     
       18. The device of  claim 15 , wherein the processor is further configured to determined, based on the acoustic cardiographic metrics, a fusion band. 
     
     
       19. The device of  claim 18 , wherein the processor is further configured to set an AV delay pacing parameter within the fusion band. 
     
     
       20. The device of  claim 15 , wherein the processor is further configured to choose an atrioventricular delay pacing parameter based on a change in heart sound S 2  timing. 
     
     
       21. The device of  claim 15 , wherein the device is an implantable medical device. 
     
     
       22. The device of  claim 15 , further comprising means for evaluating at least one of the indications of hypertension and means for generating a diagnosis of hypertension based on the evaluation of the at least one indication of hypertension. 
     
     
       23. The device of  claim 22 , further comprising means for providing the diagnosis of hypertension to a remote device. 
     
     
       24. The device of  claim 22 , further comprising means for modifying the set of cardiac pacing parameters in response to the diagnosis of hypertension. 
     
     
       25. A device comprising:
 a heart sound sensor configured to obtain a heart sound signal; 
 an electrogram (EGM) sensor configured to obtain an electrogram; and 
 a processor configured to generate one or more acoustic cardiographic metrics based on at least one of the heart sound signal received from the heart sound sensor and the EGM received from the EGM sensor for a set of cardiac pacing parameters, wherein the acoustic cardiographic metrics include one or more of: 
 an indication of atrioventricular (AV) dyssynchrony based on at least an interval from heart sound S 2  to heart sound S 1 ; 
 an indication of interventricular (VV) dyssynchrony based on a splitting of at least one of heart sound S 1  and heart sound S 2 ; 
 an indication of left intraventricular dyssynchrony based on at least one of
 electromechanical activation delay (EMAT), 
 EMAT plus S 1  duration, 
 heart sound M 1  duration, and 
 heart sound A 2  duration, 
 
 a surrogate for a myocardial performance index (MPI) based at least on a duration heart sound S 1  and a duration of heart sound S 2 ; 
 an indication of left ventricle (LV) filling time based on the interval between heart sound S 2  and heart sound S 1 ; and 
 an indication of LV contractility based on at least one of:
 the ratio of EMAT plus heart sound S 1  duration divided by the interval between heart sound S 1  and heart sound S 2 ; 
 the ratio of EMAT plus S 1  duration divided by an R to R interval of the EGM: 
 an indication of hypertension based on at least one of:
 heart sound S 1  splitting and heart sound S 2  splitting, 
 relative changes of intensity of M 1  and heart sound T 1  over a predetermined period of time, 
 relative change in a A 2  to heart sound P 2  amplitude ratio over a predetermined period of time, 
 
 variability in Q wave to heart sound A 2  interval (Q-A 2 ) over time, or heart sound S 4 ; and 
 
 wherein the processor is further configured to adjust one or more cardiac pacing parameters based on the indication of LV fill time to obtain an interval between S 2  and S 1  that is greater than 40% of an R to R interval of the EGM. 
 
     
     
       26. The device of  claim 25 , wherein the processor is further configured to adjust one or more of the cardiac pacing parameters based on at least one acoustic cardiographic metric. 
     
     
       27. The device of  claim 25 , further comprising memory configured to store acoustic cardiographic metric values, and wherein the processor is further configured to evaluate at least one of the cardiac pacing parameters based on at least one acoustic cardiographic metric, the evaluation comprising:
 varying the at least one cardiac pacing parameter over a predetermined range at a predetermined interval, 
 providing to the memory, for storage, a corresponding acoustic cardiographic metric value for each variation of the at least one cardiac pacing parameter; and 
 comparing the stored acoustic cardiographic metric values. 
 
     
     
       28. The device of  claim 25 , further comprising a signal generator configured to provide pacing according to the set of cardiac pacing parameters. 
     
     
       29. The device of  claim 28 , wherein the signal generator is configured to provide cardiac resynchronization therapy. 
     
     
       30. The device of  claim 25 , wherein the processor is further configured to evaluate at least one of the indications of hypertension, and based on the evaluation of the at least one indication of hypertension, generate a diagnosis of hypertensions. 
     
     
       31. The device of  claim 30 , further comprising a telemetry module configured to provide the diagnosis of hypertension to a remote device. 
     
     
       32. The device of  claim 30 , wherein the processor is further configured to modify the set of cardiac pacing parameters in response to the diagnosis of hypertension. 
     
     
       33. A method comprising:
 obtaining heart sounds from an implanted heart sound sensor; 
 obtaining an electrogram (EGM) from electrodes of an implantable device; 
 generating one or more acoustic cardiographic metrics based on at least one of the heart sounds and the electrogram for a set of cardiac pacing parameters, the set of cardiac pacing parameters including a plurality of pacing parameters; 
 wherein the acoustic cardiographic metrics include an indication of interventricular (VV) dyssynchrony based on a splitting of at least one of heart sound S 1  and heart sound S 2 ; 
 wherein the acoustic cardiographic metric comprising the indication of VV dyssynchrony is based on the splitting of heart sound S 1  and heart sound S 2 , the method further comprising adjusting one or more cardiac pacing parameters to obtain an S 1  split between heart sound M 1  and heart sound T 1  that is between approximately 20 and 40 ms and an S 2  split between heart sound A 2  and heart sound P 2  that is approximately 20 ms. 
 
     
     
       34. A device comprising:
 a heart sound sensor configured to obtain a heart sound signal; 
 an electrogram (EGM) sensor configured to obtain an electrogram; and 
 a processor configured to generate one or more acoustic cardiographic metrics based on at least one of the heart sound signal received from the heart sound sensor and the EGM received from the EGM sensor for a set of cardiac pacing parameters, wherein the acoustic cardiographic metrics include an indication of interventricular (VV) dyssynchrony based on a splitting of at least one of heart sound S 1  and heart sound S 2 ; 
 wherein the acoustic cardiographic metric comprises the indication of VV dyssynchrony, and is based on the splitting of heart sound S 1  and heart sound S 2 , and the processor is further configured to one or more cardiac pacing parameters to obtain an S 1  split between heart sound M 1  and heart sound T 1  that is between approximately 20 and 40 ms and an S 2  split between heart sound A 2  and heart sound P 2  that is approximately 20 ms. 
 
     
     
       35. A method comprising:
 obtaining heart sounds from an implanted heart sound sensor; 
 obtaining an electrogram (EGM) from electrodes of an implantable device; 
 generating one or more acoustic cardiographic metrics based on at least one of the heart sounds and the electrogram for a set of cardiac pacing parameters, the set of cardiac pacing parameters including a plurality of pacing parameters; 
 wherein the acoustic cardiographic metrics include an indication of interventricular (VV) dyssynchrony based on a splitting of at least one of heart sound S 1  and heart sound S 2 ; 
 wherein the acoustic cardiographic metric comprising the indication of VV dyssynchrony is based on the splitting of heart sound S 1  and heart sound S 2 , the method further comprising adjusting one or more cardiac pacing parameters to obtain an S 1  split between heart sound M 1  and heart sound T 1  that is between approximately 20 and 40 ms. 
 
     
     
       36. A device comprising:
 a heart sound sensor configured to obtain a heart sound signal; 
 an electrogram (EGM) sensor configured to obtain an electrogram; and 
 a processor configured to generate one or more acoustic cardiographic metrics based on at least one of the heart sound signal received from the heart sound sensor and the EGM received from the EGM sensor for a set of cardiac pacing parameters, wherein the acoustic cardiographic metrics include an indication of interventricular (VV) dyssynchrony based on a splitting of at least one of heart sound S 1  and heart sound S 2 ; 
 wherein the acoustic cardiographic metric comprises the indication of VV dyssynchrony, and is based on the splitting of heart sound S 1  and heart sound S 2 , and the processor is further configured to one or more cardiac pacing parameters to obtain an S 1  split between heart sound M 1  and heart sound T 1  that is between approximately 20 and 40 ms. 
 
     
     
       37. A method comprising:
 obtaining heart sounds from an implanted heart sound sensor; 
 obtaining an electrogram (EGM) from electrodes of an implantable device; generating one or more acoustic cardiographic metrics based on at least one of the heart sounds and the electrogram for a set of cardiac pacing parameters, the set of cardiac pacing parameters including a plurality of pacing parameters; 
 wherein the acoustic cardiographic metrics include an indication of interventricular (VV) dyssynchrony based on a splitting of at least one of heart sound S 1  and heart sound S 2 ; 
 wherein the acoustic cardiographic metric comprising the indication of VV dyssynchrony is based on the splitting of heart sound S 1  and heart sound S 2 , the method further comprising adjusting one or more cardiac pacing parameters to obtain an S 2  split between heart sound A 2  and heart sound P 2  that is approximately 20 ms. 
 
     
     
       38. A device comprising:
 a heart sound sensor configured to obtain a heart sound signal; 
 an electrogram (EGM) sensor configured to obtain an electrogram; and 
 a processor configured to generate one or more acoustic cardiographic metrics based on at least one of the heart sound signal received from the heart sound sensor and the EGM received from the EGM sensor for a set of cardiac pacing parameters, wherein the acoustic cardiographic metrics include an indication of interventricular (VV) dyssynchrony based on a splitting of at least one of heart sound S 1  and heart sound S 2 ; 
 wherein the acoustic cardiographic metric comprises the indication of VV dyssynchrony, and is based on the splitting of heart sound S 1  and heart sound S 2 , and the processor is further configured to one or more cardiac pacing parameters to obtain an S 2  split between heart sound A 2  and P 2  that is approximately 20 ms.